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Added 12 languages with automatic phone-language selection and English fallback. Choose a language in Settings. Localized app names, calculator labels, results and messages.
40 offline electrical calculators: voltage drop, wire size, Ohm's law & power.
Electrical Calculator Toolbox gives electricians, technicians, engineers, students and DIY users 40 fast calculation tools in one fully offline Android app. Use it on site, at the workbench or while studying. Calculate voltage drop, wire size, Ohm's law, watts, volts, amps, three-phase power, energy cost and more without an account, ads or an internet connection. ELECTRICAL CALCULATORS • Ohm's law: voltage, current, resistance and power • Watts, volts and amps conversion for DC, single-phase and three-phase systems • Voltage drop, load voltage, cable loss and conductor recommendation • NEC AWG and IEC mm² wire size estimates • Three-phase power, kW, kVA, amps and power factor • Motor full-load current and transformer sizing • Conduit fill and main-panel capacity • Power factor correction ELECTRONICS TOOLS • Resistor color code and SMD resistor code • Capacitor code calculator • LED resistor calculator with safe E12 selection • Series and parallel resistors or capacitors • Voltage and current dividers • RC filter cutoff and 555 timer • Battery life calculator ENERGY, SOLAR AND EV TOOLS • Appliance electricity cost and electricity bill estimates • Time-of-use tariff and contracted-power comparison • Solar self-consumption and export value • Home battery backup runtime • 12 V, 24 V and 48 V inverter cable sizing • EV charging time, charging cost and charger load sharing • Peak power and main-fuse estimate HEATING AND COOLING • Heat pump electrical load and running cost • Room heating and underfloor heating cable • Sauna heater sizing • Air-conditioner BTU size and seasonal running-cost estimate BUILT FOR QUICK FIELD USE • 40 native electrical and electronics calculators • Fully offline after installation • No sign-in, account or subscription • No ads, analytics or tracking • No internet or sensitive Android permissions • Favorites and recently used tools • Search and categories • Light, dark and system themes • Clear units, validation and safety notes Electrical Calculator Toolbox works as an electrician calculator, electrical engineering calculator, voltage drop calculator, wire size calculator and Ohm's law calculator in one compact toolkit. Results are planning and educational estimates. Always verify conductor sizing, protective devices, derating, installation conditions and other results against current local electrical codes, equipment instructions and a qualified electrician or engineer before performing electrical work. Available in English, German, French, Spanish, Portuguese, Italian, Dutch, Japanese, Korean, Traditional Chinese (Taiwan), Thai, Vietnamese and Malay. The app follows your phone language when supported and uses English otherwise. You can change the language in Settings.